1. Field of the Invention
This invention relates to a method of determining errors in data values. More particularly, this invention relates to a method of determining errors in data transmitted in a high-speed bit stream. Still more particularly, this invention relates to a method of analyzing data surrounding errors in a high-speed bit stream.
2. Relevant Art
There are many ways to transmit data from one location to another, but the most common means of transmission in the current era is through digital transmission. The electronic circuitry in computers, digital telephones and other types of electronic equipment detects the difference between two states (high voltage and low voltage), and represents these states as one of the two numbers in a binary system, 1 or 0. A bit is the basic unit of information in a binary numbering system. A byte is eight bits.
Building a reliable circuit that tells the difference between 1 and 0 is relatively easy, thus computers and other digitally operated electronic devices are reasonably accurate in their internal processing capabilities. However, errors do occur for a number of reasons. For example, component parts in equipment sometimes fail. When that happens, it is important to be able to trouble shoot to determine which component part failed. This is sometimes possible to do by analyzing the digital data stream generated as it passes through the piece of equipment.
Whenever data is being transferred from one location to another, as in telecommunications where bit information in the form of bit streams is transferred over long distances, it is important to be able to detect and fully understand the nature of each of these errors occuring in the bit (data) stream.
Bit error testers are used to measure the quality of storage and communication of digital information. Early bit error testers simply counted the number of errors found during a measurement and, along with knowing the number of bits that were looked at during the measurement, would display the average error rate. Representative art includes U.S. Pat. No. 3,976,864, which discloses apparatus and a method for testing digital circuits. U.S. Pat. No. 4,060,797 discloses a serial bit stream code detector. U.S. Pat. No. 4,847,877 discloses a method and apparatus for detecting a predetermined bit pattern within a serial bit stream. U.S. Pat. No. 4,507,783 discloses error detection circuitry for digital systems.
A previous invention by these inventors, namely U.S. Pat. No. 5,414,713 is incorporated herein by reference in its entirety. That patent discloses a device having the ability to identify, log and study error location information in digital channels. This error location information comprises a list of each bit location where errors in the data stream occur. Error events in and of themselves can identify the location of errors inside a data stream, but they do not define the actual data that is being transmitted when the error occurs. The value of the data at and around, i.e., surrounding, errors is additional information that can be used along with the bit error location to more completely analyze errors to determining their cause. Knowledge of this kind is necessary in order for improved devices to be designed and manufactured, and for ongoing quality control during the transmission of data.
Knowing what the data values are in relation to error locations enables studying correlations between the errors and the data patterns. Creating a way to know where all errors occur in a data stream and a means to calculate what the data is at or around the error location is the subject of this invention.
It is an object of this invention to provide a method for determining the location of errors in a digital data stream.
It is also an additional object of this invention to provide a method for calculating the data values at and adjacent to the location of errors in a digital data stream.
It is a still further object of the invention to provide a method of analyzing the data surrounding an error or errors in a digital data stream.
In accordance with the above objects and those that will be mentioned and will become apparent below, the invention comprises:
A method for determining the location of at least one error in a digital data stream and identifying the data on both sides of the error which comprises:
(a) selecting a user data stream to be analyzed for errors, said data stream consisting of a linear bit stream of 0""s and 1""s in a predetermined sequence,
(b) selecting a bit seed segment out of said data stream, and converting said bit seed segment into a reference data stream,
(c) synchronizing said reference data stream with said user data stream to be tested and simultaneously storing additional information about phase and data type of said user data stream into a computer memory bank,
(d) determining if an error exists,
(e) if an error exists calculating where on the user data stream said error occurred,
(f) analyzing the data surrounding the error that is stored in the computer memory bank, and
(g) computing actual data values from phase, data type and error location.
In a preferred embodiment of the invention, a 32-bit wide data stream is used as the user""s input data and the locally created reference bit stream.
It is an advantage of this invention to a provide a method of determining the location of errors in a data stream, and of calculating the data values adjacent or surrounding the error(s) in order for more accurate information to be obtained about the location of the error(s). The method of the invention enables better maintenance of equipment, and more efficient and reliable transmission of digital data to be obtained.